U.S. patent application number 11/489621 was filed with the patent office on 2007-02-01 for recording medium.
This patent application is currently assigned to Canon Finetech Inc.. Invention is credited to Tadashi Fujii, Tatsuo Hiyoshi, Kenichi Kawano.
Application Number | 20070026170 11/489621 |
Document ID | / |
Family ID | 37694660 |
Filed Date | 2007-02-01 |
United States Patent
Application |
20070026170 |
Kind Code |
A1 |
Kawano; Kenichi ; et
al. |
February 1, 2007 |
Recording medium
Abstract
A recording medium has an ink-receiving layer provided on at
least one surface of a substrate, wherein the substrate comprises a
base material, and a resin layer having ink absorbency and/or ink
permeability formed at least on the side of the base material on
which the ink-receiving layer is provided, and wherein the resin
layer has a contact angle with respect to water of 60.degree. or
smaller, a water vapor transmission rate of 100 g/m.sup.2/24 hr or
larger according to JIS-Z-0208 and the thickness of 10 to 100
.mu.m.
Inventors: |
Kawano; Kenichi; (Fukui-shi,
JP) ; Fujii; Tadashi; (Yokohama-shi, JP) ;
Hiyoshi; Tatsuo; (Tokyo, JP) |
Correspondence
Address: |
FITZPATRICK CELLA HARPER & SCINTO
30 ROCKEFELLER PLAZA
NEW YORK
NY
10112
US
|
Assignee: |
Canon Finetech Inc.
Mitsukaido-shi
JP
|
Family ID: |
37694660 |
Appl. No.: |
11/489621 |
Filed: |
July 20, 2006 |
Current U.S.
Class: |
428/32.34 |
Current CPC
Class: |
B41M 5/506 20130101 |
Class at
Publication: |
428/032.34 |
International
Class: |
B41M 5/40 20060101
B41M005/40 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 26, 2005 |
JP |
2005-216533 (PAT. |
Jun 16, 2006 |
JP |
2006-167645 (PAT. |
Claims
1. A recording medium having an ink-receiving layer provided on at
least one surface of a substrate, wherein the substrate comprises a
base material, and a resin layer having ink absorbency and/or ink
permeability formed at least on the side of the base material on
which the ink-receiving layer is provided, and wherein the resin
layer has such a contact angle with respect to water, a water vapor
transmission rate according to JIS-Z-0208 and a thickness as to
satisfy the following relationships (1) to (3): contact angle of
resin layer.ltoreq.60.degree. (1) water vapor transmission rate of
resin layer.gtoreq.100 g/m.sup.2/24 hr (2) 10
.mu.m.ltoreq.thickness of resin layer.ltoreq.100 .mu.m (3).
2. The recording medium according to claim 1, wherein the resin
layer includes as a major component at least one resin selected
from the group consisting of cellulose and a derivative thereof; a
vinyl polymer such as polyvinyl alcohol and ethylene-vinyl alcohol
copolymer; an acrylic polymer such as polyacrylonitrile and
(meth)acrylates; and a polysulfone polymer.
3. The recording medium according to claim 1, wherein the
ink-receiving layer includes inorganic fine particles, and a
water-soluble resin and/or water-dispersible resin.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a recording medium which
enables recording of an image with high glossiness and high quality
superior in image density and ink absorbency, and effectively
prevents the image from bleeding under high-temperature and
high-humidity environment.
[0003] 2. Description of the Related Art
[0004] With an ink jet recording system, droplets of ink are
generated and caused to fly by using various ink ejection systems
such as an electrostatic attraction system, a system of applying
mechanical vibration or displacement to the ink with the use of an
piezoelectric element and a system of heating and bubbling the ink
to utilize the pressure, and then the ink droplets are applied onto
a recording medium such as paper or a plastic film having an
ink-receiving layer formed thereon to conduct recording. The
printing system makes little noise and can make a multicolor
printing at a high speed, so that it has become rapidly widespread
in recent years.
[0005] As an ink jet recording device using such an ink jet
recording system improves its performances such as speeding-up of
recording operation and recording with higher resolution, advanced
characteristics are required to a recording medium. Such
characteristics include:
(1) having excellent adhesiveness between an ink-receiving layer
and a substrate;
(2) causing little change in the characteristics caused by the
change of temperature and humidity, and no curling;
(3) causing no blocking;
(4) producing a high optical density of printed dots as well as a
vivid and bright color tone;
(5) producing a printed image with high chroma (no somberness);
(6) providing dots with an approximately perfectly circular shape
with its perimeter being smooth;
(7) having high ink-absorption capacity (a high absorption rate and
a large absorption capacity);
(8) having excellent water resistance in the ink-receiving layer
and a printed part of the printed image;
(9) imparting excellent light resistance to the printed part of the
printed image; and
(10) keeping the printed image stable and causing no change in the
image under high-temperature and high-humidity environment.
[0006] In addition, a transparent recording medium such as OHP is
required to have transparency not only of a film of a substrate but
also of an ink-receiving layer. Similarly, a white substrate such
as a white film and a resin-coated paper coated with a resin such
as polyethylene on both faces of the base paper is required to have
an ink-receiving layer superior in transparency so as not to impair
the whiteness and glossiness of the substrate in itself.
Furthermore, a glossy paper for providing a photo-like
high-resolution recorded article is required to show glossiness,
surface smoothness and texture similar to photographic paper for a
silver halide photograph.
[0007] However, these various characteristics often have a
trade-off relationship, and it has been conventionally difficult to
simultaneously satisfy them with a well-known technology.
Particularly, a recording medium using resin-coated paper as a
substrate, which is predominant from the viewpoint of glossiness
and texture, has had such a problem that when it has an image
recorded with an ink containing a water-soluble dye as a coloring
material and is preserved under high-temperature and high-humidity
environment for a long period of time, the dye bleeds and the image
quality deteriorates.
[0008] As a method for solving such a problem, many methods have
been previously proposed. For instance, Japanese Patent Application
Laid-Open No. S59-198186 and Japanese Patent Application Laid-Open
No. S59-198188 propose a method of incorporating polyethyleneimine
in a base material or a coating layer on a base material; Japanese
Patent Application Laid-Open No. S61-61887, Japanese Patent
Application Laid-Open No. S61-72581, Japanese Patent Application
Laid-Open No. S61-252189 and Japanese Patent Application Laid-Open
No. S62-174184 propose a method of using polyallylamine as a
mordant; Japanese Patent Application Laid-Open No. S63-307979
proposes a method of providing a layer which contains a mordant of
a hydrophilic polymer having tertiary or quaternary nitrogen atoms
and a polymer containing a vinyl monomer unit containing a
hydrophilic group; Japanese Patent Application Laid-Open No.
S63-162275 proposes a method of applying or impregnating a cationic
polymer and a cationic surface active agent onto or into a
substrate; Japanese Patent Application Laid-Open No. H06-143798
proposes a method of providing a dye-fixing layer mainly containing
a polymer of a quaternary ammonium salt and a cation-modified
polyvinyl alcohol; and Japanese Patent Application Laid-Open No.
H08-142496 provides a method of employing particular two cationic
polymers together. In addition; a method of adding a polymer or
compound containing a particular tertiary or quaternary nitrogen
atom into an ink-receiving layer is described in Japanese Patent
Application Laid-Open No. S59-20696, Japanese Patent Application
Laid-Open No. S59-33176, Japanese Patent Application Laid-Open No.
S59-33177, Japanese Patent Application Laid-Open No. S59-96987,
Japanese Patent Application Laid-Open No. S59-155088, Japanese
Patent Application Laid-Open No. S60-11389, Japanese Patent
Application Laid-Open No. S60-49990, Japanese Patent Application
Laid-Open No. S60-83882, Japanese Patent Application Laid-Open No.
S60-109894, Japanese Patent Application Laid-Open No. S61-277484,
Japanese Patent Application Laid-Open No. S61-293886, Japanese
Patent Application Laid-Open No. S62-19483, Japanese Patent
Application Laid-Open No. S62-198493, Japanese Patent Application
Laid-Open No. S63-49478, Japanese Patent Application Laid-Open No.
S63-115780, Japanese Patent Application Laid-Open No. S63-203896,
Japanese Patent Application Laid-Open No. S63-274583, Japanese
Patent Application Laid-Open No. S63-280681, Japanese Patent
Application Laid-Open No. S63-260477, Japanese Patent Application
Laid-Open No. H01-9776, Japanese Patent Application Laid-Open No.
H01-24784, Japanese Patent Application Laid-Open No. H01-40371,
Japanese Patent Application Laid-Open No. H03-133686, Japanese
Patent Application Laid-Open No. H06-234268, Japanese Patent
Application Laid-Open No. H07-125411, Japanese Patent Application
Laid-Open No. H08-318672 and Japanese Patent Application Laid-Open
No. H10-029369.
[0009] Any of the above described methods is a technology for
preventing the bleeding of an image under high-temperature and
high-humidity environment by combining an anionic dye with a
cationic polymer to insolubilize the dye in water, but needs a
large quantity of the cationic polymer in order to obtain a
sufficient effect, which results in relatively increasing the
amount of the cationic polymer in an ink-receiving layer. Thus, the
increased amount of the cationic polymer causes a problem of
decreasing voids in a porous (void type) ink-receiving layer
containing inorganic fine particles and degrading ink absorbency.
In addition, most cationic polymers have a tendency to increase the
viscosity of a coating slip for forming the ink-receiving layer
containing inorganic fine particles, though depending on molecular
weight and cationized degree of the cationic polymer. As the amount
of added cationic polymers increases, the above tendency also
increases and the coating stability of the coating slip is
remarkably degraded. As a result, the increased amount of the
cationic polymer has caused the problem of aggravating the
smoothness of the ink-receiving layer on the surface of a coated
film and decreasing the glossiness of a formed image.
[0010] On the other hand, among recording media classified as
glossy paper, there is a recording medium having an ink-receiving
layer formed on a substrate having water absorbency such as paper
and coat paper with a cast method. Such a type of a recording
medium has an advantage of having excellent ink absorbency and
hardly causing bleeding of an image under high-temperature and
high-humidity environment in comparison with the recording medium
using a film and a resin-coated paper as a substrate. However, the
recording medium having the ink-receiving layer placed on the
water-absorptive substrate has a problem of having difficulty in
controlling curling, degrading glossiness in a printing part, and
causing cockling in the recording medium when a large quantity of
ink was shot in. Furthermore, the recording medium produced by the
cast method has its ink-receiving layer smoothed by contacting the
layer in a wet state with a heated mirror-surface roll in the
production process, but the process was less advantageous from the
viewpoint of cost than a recording medium based on a film or a
resin-coated paper requiring no such smoothing treatment, because
of a decreased speed and a lower productivity in producing the
recording medium.
[0011] Further features of the present invention will become
apparent from the following description of exemplary
embodiments.
SUMMARY OF THE INVENTION
[0012] The present invention is designed in the light of the above
described circumstances and is directed to a recording medium which
enables recording of an image with high glossiness and high quality
superior in image density and ink absorbency, and effectively
prevents the image from bleeding out under high-temperature and
high-humidity environment.
[0013] As a result of extensive research for obtaining a recording
medium which has an ink-receiving layer formed thereon superior in
glossiness without smoothing treatment, has excellent image density
and ink absorbency, and hardly causes bleeding on an image under
high-temperature and high-humidity environment, the present
inventors found that a plurality of the above described problems
are simultaneously solved by providing a resin layer having ink
absorbency and/or ink permeability on a base material and by
controlling the contact angle with respect to water, the water
vapor transmission rate according to JIS-Z-0208 and the thickness
of the resin layer into a particular range, and accomplished the
present invention.
[0014] Specifically, the present invention provides a recording
medium having an ink-receiving layer provided on at least one
surface of a substrate, wherein the substrate comprises a base
material, and a resin layer having ink absorbency and/or ink
permeability formed at least on the side of the base material on
which the ink-receiving layer is provided; and the resin layer
formed on the base material has such a contact angle with respect
to water, a water vapor transmission rate according to JIS-Z-0208
and a thickness as to satisfy the following relationships (1) to
(3). contact angle of resin layer.ltoreq.60.degree. (1) water vapor
transmission rate of resin layer.gtoreq.100 g/m.sup.2/24 hr (2) 10
.mu.m.ltoreq.thickness of resin layer.ltoreq.100 .mu.m (3)
[0015] It is preferable for the above-described recording medium
according to the present invention that a resin layer mainly
includes at least one resin selected from the group consisting of
cellulose and a derivative thereof; a vinyl polymer such as
polyvinyl alcohol and ethylene-vinyl alcohol copolymer; an acrylic
polymer such as polyacrylonitrile and (meth)acrylates; and a
polysulfone polymer, and that an ink-receiving layer includes
inorganic fine particles, and a water-soluble resin and/or a
water-dispersible resin.
[0016] The above described constitution according to the present
invention can provide a recording medium that has an ink-receiving
layer on which a high-gloss image is formed without needing
smoothing treatment, can conduct high-quality image recording
superior in image density and ink absorbency recorded thereon, and
effectively prevents an image from bleeding under high-temperature
and high-humidity environment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0017] The present invention will be described in more detail with
reference to the best mode for carrying out the invention.
[0018] A base material to be used in the present invention is not
limited in particular but includes, for instance, a material made
of paper such as adequately-sized paper, unsized paper, coat paper,
cast-coated paper and a resin-coated paper of which one or both
surfaces are coated with a resin such as polyolefin (hereafter
referred to as "resin-coated paper"); a transparent thermoplastic
resin film such as polyethylene, polypropylene, polyester,
polylactic acid, polystyrene, polyacetate, polyvinyl chloride,
cellulose acetate, polyethylene terephthalate, polymethyl
methacrylate and polycarbonate; a sheet material (synthetic paper
or the like) composed of a film opacified by filling it with an
inorganic substance or by fine voids; a cloth; and besides, a sheet
composed of glass or metal.
[0019] When the base material in itself needs to have a high
liquid-absorbency (absorbency particularly for an aqueous ink or a
water-soluble solvent in the aqueous ink) from the viewpoint of ink
absorbency, paper or cloth can be preferably used among the above
described base materials. Here, the water-soluble solvent means
water, or a mixture of water and an organic solvent miscible with
water. The organic solvent miscible with water includes, for
instance, an alcohol such as methanol, ethanol and propanol; a
lower alkyl ether of a polyhydric alcohol such as ethyleneglycol,
diethylene glycol, ethyleneglycolmonomethyl ether and
ethyleneglycoldimethyl ether; a ketone such as acetone and
methylethylketone; and an ether such as tetrahydrofuran.
[0020] A substrate according to the present invention is obtained
by forming a resin layer on the above described base material. When
producing a recording medium capable of imparting image quality
equal to that of a silver halide photograph by improving the
smoothness of the surface of the resin layer and further improving
the glossiness of an ink-receiving layer formed on the resin layer,
it is preferable to employ a highly smooth base material such as
woodfree paper, coat paper, art paper and cast-coated paper, among
the above described base materials with liquid-absorbency.
Particularly, a base material preferably has a Bekk smoothness of
10 seconds or longer defined by JIS-P-8119, more preferably 50
seconds or longer, and still more preferably 100 seconds or
longer.
[0021] The thickness of a base material is not limited in
particular, but is preferably in a range of 25 to 500 .mu.m, and
more preferably is in a range of 50 to 300 .mu.m. When the base
material is thinner than 25 .mu.m, an obtained recording medium
haves low rigidity and produces inconvenience such as causing
insufficient touch and texture when touched with hands and causing
insufficient opacity. On the contrary, when the base material is
thicker than 500 .mu.m, an obtained recording medium becomes rigid
and may interfere with the feeding and traveling of paper in a
printer. The weight of the base material is not limited either in
particular, but is preferably in a range of about 25 to 500
g/m.sup.2.
[0022] The substrate according to the present invention is obtained
by forming a resin layer having ink absorbency and/or ink
permeability (which means absorbency or permeability for aqueous
ink or a water-soluble solvent in the aqueous ink in particular,
and hereafter is referred to as just "ink permeability" unless
otherwise indicated), on at least one surface of the above
described base material.
[0023] It is preferable that a resin layer formed on a base
material is comprised mainly of a hydrophilic polymer which has
high wettability to aqueous ink and can make aqueous ink
(particularly, water-soluble solvent in ink) be absorbed therein or
permeate therethrough. The hydrophilic polymer includes, for
instance, cellulose; a cellulose derivative (such as a cellulose
ester (a cellulose acetate such as cellulose diacetate and
cellulose triacetate), an organic ester like cellulose propionate,
cellulose butyrate, cellulose acetate propionate, cellulose acetate
butyrate and cellulose acetate phthalate, an inorganic ester like
cellulose nitrate, cellulose sulfate and cellulose phosphate, and a
mixed acid ester like cellulose nitrate acetate), and a cellulose
ether (ethyl cellulose)); a vinyl polymer (such as polyvinyl
acetate and a completely or partially saponificated substance
thereof (polyvinyl alcohol or the like), and an
ethylene-vinylacetate copolymer and a completely or partially
saponificated compound thereof (ethylene-vinylalcohol copolymer));
an acrylic polymer (such as polyacrylonitrile, poly(meth) acrylate,
polyacrylamide and poly N-methylacrylamide); polyvinylpyrrolidone;
polyalkylene oxide (polyethylene glycol and the like); a
polyalkylvinyl ether (polymethylvinyl ether and the like); a
carboxyl-group-containing polymer or a salt thereof
(styrene-maleicanhydride copolymer), (meth)alkylacrylate
ester-(meth)acrylic acid copolymer, methylvinylether-maleic
anhydride copolymer and the like), a polysulfone polymer
(polysulfone, polyethersulfone and the like); polyamide; and
polyethyleneimine. These hydrophilic polymers can be used singly or
in combination of two or more of them.
[0024] Among the above described polymers can be preferably used
cellulose and a derivative thereof; an acrylic polymer such as
polyacrylonitrile and (meth)acrylates; and a polysulfone polymer,
which are used as a material of a so-called semi-permeable
membrane; and a vinyl polymer such as polyvinyl alcohol and
ethylene-vinyl alcohol copolymer, since all those polymers are
particularly excellent in showing the effect of inhibiting an image
from bleeding under high-temperature and high-humidity environment
which characterizes the substrate according to the present
invention.
[0025] The resin layer mainly containing the above described
hydrophilic polymer should have a contact angle of less than
80.degree. with respect to water, but the resin layer according to
the present invention has a contact angle of 60.degree. or less,
and preferably of 40.degree. or less, from the viewpoint of
improving the ink permeability of the resin layer. The contact
angle in the above description means an angle formed between a
tangent line of a droplet of water and a polymer surface at the
point of intersection of the resin layer with the surface of the a
droplet of water put on the surface of the resin layer; and
accordingly the smaller the angle is, the higher the wettability of
the resin layer to aqueous ink is. The value of the contact angle
in the present invention is obtained by the steps of leaving a film
composed of the above described hydrophilic polymer in an
environment of 23.degree. C. and 50% RH for 12 hours; dropping 2
.mu.l of pure water onto the film; leaving the droplet until it
spreads to the maximum radius (after a lapse of 0.1 to 60 seconds
after drop) in such a range that a fluid volume does not change (in
such a range that the droplet is not absorbed by the film and does
not vaporize); and when it reached this point, measuring the angle
with the use of a contact angle measurement device. An automatic
contact angle meter CA-VP (made by Kyowa Interface Science Co.,
Ltd.) was used for measuring the contact angle in the present
invention.
[0026] In addition, the resin layer according to the present
invention has a water vapor transmission rate of 100 g/m.sup.2/24
hr or more when measured according to JIS-Z-0208 and preferably of
300 g/m.sup.2/24 hr or more, in order to sufficiently make a
recording medium show the effect specific to the present invention
of acquiring an improved ink permeability of the resin layer and
inhibiting an image from bleeding under high-temperature and
high-humidity environment. In the above description, the water
vapor transmission rate in the present invention is a value
measured at a temperature-humidity condition (temperature:
40.degree. C. and humidity: 90% RH) which is prescribed in
JIS-Z-0208.
[0027] A substrate to be used in the present invention has a resin
layer formed on a base material with a thickness of 10 to 100 .mu.m
and preferably of 10 to 50 .mu.m. When having the thickness below
10 .mu.m, the resin layer may have nonuniform ink absorbency
because of formation of a defect such as a pinhole or may have the
degraded smoothness of the surface of the resin layer because
unevenness on the surface of a base material is not flattened,
while the substrate is produced. On the contrary, when having a
thickness over 100 .mu.m, the resin layer may have low ink
absorbency. Accordingly, the resin layer preferably has a thickness
in the above described range and a surface roughness (maximum
height (R.sub.y) according to JIS-B-0601) higher than that of the
base material, in order to make the surface thereof smoother and
further to make the ink-receiving layer formed thereon more
glossy.
[0028] The inventive method for forming a resin layer on a base
material includes: a method of appropriately selecting a preferred
hydrophilic polymer described above, dissolving or dispersing it in
a suitable solvent, and applying it on the base material; a method
of forming a film composed of the hydrophilic polymer, and
laminating the film on the base material; and a method of
laminating the film on the base material with an extrusion process.
A coating slip having a hydrophilic polymer dissolved/dispersed
therein may be applied by roll coating, blade coating, air knife
coating, gate roll coating, bar coating, size press coating, a
symsizer, spray coating, gravure coating, curtain coating or the
like. An adhesive to be used in lamination includes an epoxy
system, a polyurethane system, a polyester system, an isocyanate
system, a phenolic system, a vinyl acetate system and an acrylic
system.
[0029] When using cellulose as a hydrophilic polymer, it is
acceptable to form a resin layer by applying/impregnating viscose
on/into a base material and producing a regenerated cellulose film
by the same method for producing viscose-processed paper, which is
similar to a conventionally well-known method for producing a
cellophane film.
[0030] The smoothness of the surface of a resin layer formed on a
base material by the above described method is not limited in
particular, but when the resin layer is used for producing such a
recording medium as to provide photo-like picture quality by
forming an ink-receiving layer on the resin layer, the surface of
the resin layer preferably has a ten-point average roughness of 0.5
.mu.m or less according to JIS-B-0601, and a 60-degree specular
glossiness of 25% or higher prescribed by JIS-Z-8741.
[0031] When an ink-receiving layer is transparent and the color of
a base material and the pattern of an uneven surface affect a
printed image, though a resin layer may be transparent,
semitransparent or opaque, it is acceptable to add various coloring
agents, a white pigment and a fluorescent brightener into the resin
layer in such a range as not to deteriorate the ink permeability of
the resin layer. The resin layer may be formed into a multilayer
consisting of layers each composed of a different type of a
hydrophilic polymer and a different composition ratio of other
additives; and can be formed on one or both surfaces of a base
material. Particularly, a substrate having the resin layer formed
on both surfaces is hardly charged with electricity even when an
ink-receiving layer is formed on one surface thereof, because the
resin layer in itself has a low surface electric resistance,
thereby eliminating a need of such an antistatic treatment as is
implemented on the rear surface of a general film and resin coat
paper. The resin layer formed of a hydrophilic polymer also has an
advantage of eliminating a need of such a treatment of converting
the surface on which the ink-receiving layer is to be formed into
an easily bondable surface as is implemented on a film having an
hydrophobic surface or a resin-coated paper, because the resin
layer has high affinity to an aqueous coating slip to be used when
an ink-receiving layer is formed thereon. Both of the above
advantageous points contribute to a cost reduction when producing a
recording medium.
[0032] When a substrate has a resin layer formed only on one
surface of a base material, it is acceptable to apply as a backcoat
or laminate any of various resins other than the hydrophilic
polymer to be used in the resin layer or alternatively a resin
containing inorganic fine particles or an antistatic agent, on the
rear surface having no resin layer formed thereon, for the purpose
of adjusting water resistance, curl balance, coefficient of
friction with the surface of an ink-receiving layer and
electrostatic chargeability due to the friction or of preventing
blocking of a recording medium, which occur when sheets of the
recording medium derived from the substrate are stacked. It is also
possible to treat the surface of the resin layer with electric
corona discharge and form a various types of an undercoat, in order
to increase the adhesive strength of the resin layer to the
ink-receiving layer formed thereon.
[0033] According to the present invention, an ink-receiving layer
containing a water-soluble resin and/or a water-dispersible resin
as well as inorganic fine particles is formed on the resin layer of
the substrate obtained as described above. The thus produced
recording medium can conduct recording of an image of high quality
superior in image density and ink absorbency recorded thereon, and
can effectively prevent the image from bleeding under
high-temperature and high-humidity environment.
[0034] Inorganic fine particles usable for forming an ink-receiving
layer according to the present invention preferably has high
ink-absorptivity, is superior in a color-developing property and
can form a high-quality image. Such inorganic fine particles
include, for instance, calcium carbonate, magnesium carbonate,
kaolin, clay, talc, hydrotalcite, aluminum silicate, calcium
silicate, magnesium silicate, diatomaceous earth, alumina,
colloidal alumina, aluminum hydroxide, alumina hydrate, synthesized
amorphous silica, colloidal silica, lithopone and zeolite. They can
be singly used or some of them can be concomitantly used.
[0035] The above described inorganic fine particles preferably have
an average particle size in a range of 50 to 500 nm and more
preferably in a range of 100 to 300 nm, in order to obtain a highly
glossy and highly transparent ink-receiving layer. When the
inorganic fine particles have the average particle size of smaller
than 50 nm, the ink-receiving layer remarkably lowers its ink
absorbency, and causes bleeding and beading of ink (phenomenon of
forming granular density irregularity because of being incapable of
absorbing ink), when the recording medium is used for printing by a
printer which ejects a large amount of ink.
[0036] On the other hand, when the inorganic fine particles have an
average particle size of larger than 50 nm, the ink-receiving layer
decreases its transparency and lowers the printing density and
glossiness of an image. The average particle size according to the
present invention is measured with a dynamic light-scattering
method, and can be determined through analysis with the use of a
cumulant method which is described in "Structure of Macromolecule
(2), Scattering Experiment and Morphological Observation, Chapter
1, Light Scattering" (Kyoritsu Shuppan Co., edited by Society of
Polymer Science, Japan) or in J. Chem. Phys., 70 (B), 15 Apl., 3965
(1979).
[0037] Preferably usable inorganic fine particles in the present
invention among the above described inorganic fine particles
includes silica, alumina and alumina hydrate, and alumina hydrate
having a boehmite structure or a pseudoboehmite structure is more
preferably usable, from the viewpoint of giving excellent
transparency and smoothness to an ink-receiving layer to be formed,
being capable of forming finer voids, and well fixing dyes in ink
because of having the particle surface with a positive charge.
[0038] Particularly, the alumina hydrate preferably has a BET
specific surface area of 50 m.sup.2/g or larger, more preferably in
a range of 50 to 500 m.sup.2/g, and further preferably in a range
of 50 to 250 m.sup.2/g. When the alumina hydrate has a BET specific
surface area in a range of 50 to 500 m.sup.2/g, the ink-receiving
layer haves superior ink absorbency and smoothness and does not
cause beading. On the other hand, when the alumina hydrate has a
BET specific surface area of smaller than 50 m.sup.2/g, the
ink-receiving layer lowers its transparency, decreases the density
of print formed thereon, and tends to produce a whitish and hazy
image of a printed article. In addition, when the alumina hydrate
has a BET specific surface area of larger than 500 m.sup.2/g the
ink-receiving layer lowers its ink absorbency and a large quantity
of an acid of a peptization agent is needed for stably dispersing
the alumina hydrate, which are undesirable.
[0039] Alumina hydrate having a boehmite structure or a
pseudoboehmite structure to be preferably used in the present
invention is expressed by the following general formula (1).
Al.sub.20.sub.3-n(OH).sub.2n.mH.sub.20 (1)
[0040] In the above formula, n is any of integers of 0, 1, 2 and 3;
and m represents a value of 0 to 10 and preferably 0 to 5, and can
be another value than an integer because mH.sub.2O mostly means a
water phase which is not involved in the formation of a crystal
lattice and can be desorbed. When this type of alumina hydrate is
calcined, m can reach a value of 0.
[0041] The crystal of alumina hydrate showing a boehmite structure
is generally a layered compound of which the (020) face forms a
huge plane and shows a characteristic diffraction peak in an X-ray
diffraction pattern. As for the boehmite structure, the alumina
hydrate can have a structure in which excess water is contained
between layers of the face (020), which is referred to as
pseudoboehmite, in addition to a complete boehmite structure. The
pseudoboehmite shows a wider diffraction peak than that of the
complete boehmite in the X-ray diffraction pattern. Because the
complete boehmite cannot be clearly distinguished from the
pseudoboehmite, both alumina hydrates are hereafter referred to as
alumina hydrate showing a boehmite structure unless otherwise
indicated.
[0042] A method for producing the above described alumina hydrate
is not limited in particular, but a usable method includes, for
instance, a Bayer process and an alum thermal-decomposition method.
A particularly preferred method is a method of adding an acid to a
long-chain aluminum alkoxide and hydrolyzing the alkoxide. The
particle shape of the resultant alumina hydrate can be controlled
into a particular range by subjecting the alumina hydrate to a
hydrothermal synthesis process and a subsequent aging process of
growing the particle, while adjusting a condition of the aging
process. Primary particles of the alumina hydrate with
comparatively uniform particle sizes are grown by properly setting
an aging period of time. The resultant sol can be directly used as
a liquid dispersion after it is blended with an acid as a
peptization agent, but can be converted into a liquid dispersion by
powdering the sol by spray-dry or the like, and adding the acid to
it, so as to improve the dispersibility of alumina hydrate into
water. An acid for peptizing alumina hydrate can be a
conventionally well-known acid for the use, and includes, for
instance, an organic acid such as formic acid, acetic acid,
propionic acid, butyric acid, glycolic acid, lactic acid, pyruvic
acid and methanesulfonic acid, and an inorganic acid such as
hydrochloric acid and nitric acid. One or more of them can be
freely selected and be used as the acid.
[0043] A liquid dispersion can be prepared by using various surface
active agents or macromolecular dispersion agents in place of acid
used, for a peptization agent. It is also acceptable to prepare the
liquid dispersion of fine particles by dispersing and peptizing
inorganic fine particles in water with the use of at least one
organic acid and cationic polymer.
[0044] The solvent for a liquid dispersion of fine particles is not
particularly limited as long as it is an aqueous medium such as
water and a mixture solution of water and an organic solvent
miscible with water. The organic solvent miscible with water
includes, for instance, an alcohol such as methanol, ethanol and
propanol; a lower alkyl ether of a polyhydric alcohol such as
ethyleneglycolmonomethyl ether and ethyleneglycoldimethyl ether; a
ketone such as acetone and methylethylketone; and an ether such as
tetrahydrofuran.
[0045] An ink-receiving layer according to the present invention is
formed by using a water-soluble resin and/or water-dispersible
resin as well as the above described inorganic fine particles. The
water-soluble resin or the water-dispersible resin to be used in
the present invention includes, for instance, gelatine, casein and
a modified compound thereof; a cellulose derivative such as
methylcellulose, carboxymethylcellulose and hydroxyethylcellulose;
completely or partially saponificated polyvinyl alcohol or a
modified compound thereof (cation-modified, anion-modified,
silanol-modified compounds and the like); an urea resin; a melamine
resin; an epoxy resin; an epichlorohydrin resin; a polyurethane
resin; a polyethyleneimine resin; a polyamide resin; a
polyvinylpyrrolidone resin; a polyvinylbutyral resin;
poly(meth)acrylic acid or a copolymer thereof; an acrylamide resin;
a maleic anhydride copolymer; a polyester resin; an SBR latex; an
NBR latex; a methylmethacrylate-butadiene copolymer latex; an
acrylic polymer latex such as an acrylate copolymer; a vinyl
polymer latex such as ethylene-vinyl acetate copolymer; and a
functional-group-modified polymer latex obtained by imparting a
cationic group or an anionic group to any of the above various
polymer latexes. A preferred water-soluble resin or
water-dispersible resin is a polyvinyl alcohol which is obtained by
hydrolyzing polyvinyl acetate and has an average polymerization
degree of 300 to 5,000. The polyvinyl alcohol has a saponification
degree of preferably 70% or more but less than 100%, and
particularly preferably of 80 to 99.5%. The above described
water-soluble resins or water-dispersible resins can be used
singly, or a plurality of them may be mixed and used.
[0046] The mixture mass ratio of the above described inorganic fine
particles (A) to the water-soluble resin and/or the
water-dispersible resin (B) is preferably A:B=1:1 to 30:1, and
further preferably is in a range of A:B=1.5:1 to 20:1. When the
mixture mass ratio of the above described inorganic fine particles
(A) to the water-soluble resin and/or water-dispersible resin (B)
is in this range, a formed ink-receiving layer hardly causes
cracking and a powdery coming-off and has adequate ink absorbency.
A method of mixing the above described inorganic fine particles
with the water-soluble resin and/or water-dispersible resin is not
limited in particular, but is preferably a method of previously
dissolving the water-soluble resin and/or water-dispersible resin
in a necessary amount of an aqueous medium and mixing it with a
liquid dispersion of fine particles. They can be mixed in any
method of a batch system and a continuous system.
[0047] For the recording medium according to the present invention,
the ink-receiving layer may contain a hardening agent, in order to
improve a film-forming capability, water resistance and film
strength of a film formed with inorganic fine particles and a
water-soluble resin and/or a water-dispersible resin. The hardening
agent can be selected from various hardening agents generally
according to the type of a reactive group in a polymer to be used.
For instance, when an ink-receiving layer employs a polyvinyl
alcohol resin, the usable hardening agent includes an epoxy
hardening agent or an inorganic hardening agent such as a boron
compound like boric acid and a water-soluble aluminum salt.
[0048] The amount of a hardening agent to be used in an
ink-receiving layer varies depending on the amount of a
water-soluble resin and/or a water-dispersible resin to be used as
a binder, but generally is 0.1 to 30.0 mass % with respect to the
amount of the water-soluble resin and/or the water-dispersible
resin. When the content of a hardening agent is less than 0.1 mass
% with respect to the content of the water-soluble resin and/or the
water-dispersible resin, the ink-receiving layer has decreased the
film-forming capability and does not provide sufficient water
resistance. On the contrary, when the content of a hardening agent
exceeds 30.0 mass %, the viscosity of a coating slip greatly
changes with time and the coating stability of the coating slip may
be lowered.
[0049] For the recording medium according to the present invention,
an ink-receiving layer may contain a cationic polymer in such a
range as not to affect the ink absorbency, in order to effectively
prevent an image from bleeding under high-temperature and
high-humidity environment. The cationic polymer can be a
conventionally well-known polymer, and includes, for instance, a
resin of polyallylamine, polyamine sulfone, polyvinylamine,
polyethyleneimine, and polyamide epichlorohydrin; a cation-modified
compound of polyvinylpyridinium halide, polydimethyldiallyl
ammonium chloride and polyacrylamide; and a copolymer of acrylic
amide and a cationic monomer, a copolymer of a vinylpyrrolidone
monomer and a different general monomer, a copolymer of a
vinyloxazolidinone monomer and a different general monomer, and a
copolymer of a vinylimidazole monomer and a different general
monomer. They can be used singly or in combination of two or more
of them.
[0050] The solid concentration of a coating slip for forming an
ink-receiving layer is not limited in particular as long as the
coating slip has a viscosity capable of forming the ink-receiving
layer on a substrate, but preferably is 5.0 to 50.0 mass % with
respect to the total mass of the coating slip. When the solid
concentration is less than 5.0 mass %, it is necessary to increase
a coating amount for thickening the film thickness of the
ink-receiving layer, which requires much time and energy for drying
and accordingly is noneconomic. When the solid concentration
exceeds 50.0 mass %, the viscosity of the coating slip increases
and may degrade the applicability.
[0051] The above described coating slip can contain various
additives in such a range as not to hinder the composition from
showing an effect of the present invention. Such an additive
includes an antifoamer, an ink fixer, a dot moderator, a coloring
agent, a fluorescent whitening agent, an antiseptic agent, a pH
regulator, a penetrant, an antistatic agent, a conductive agent, an
ultraviolet-absorbing agent and an antioxidant (a color-fading
inhibitor).
[0052] A prepared coating slip can be applied on a substrate with a
conventionally well-known coating method such as a roll coating
method, a blade coating method, an air-knife coating method, a
gate-roll coating method, a bar coating method, a size pressing
method, a spin coating method, a spray coating method, a gravure
coating method, a curtain coater method and a die coating method.
An ink-receiving layer can be formed by subsequently drying the
coated slip with the use of a drying device such as a hot air
dryer, a heat drum and a far infrared ray dryer. The ink-receiving
layer of a recording medium according to the present invention may
be formed into a multilayer by changing the composition ratio among
inorganic fine particles, a binder and other additives in each
layer. It can be also formed on both surfaces of the substrate as
well as on one surface. The ink-receiving layer may be smoothed
with the use of an apparatus such as a calendar and a cast, for the
purpose of improving the resolution of an image and
transportability.
[0053] The amount of a coating slip to be applied onto a substrate
is preferably in a range of 0.5 to 60.0 g/m.sup.2 in terms of solid
content, and more preferably is in a range of 5.0 to 55.0
g/m.sup.2. When the applied amount is less than 0.5 g/m.sup.2, ink
may flow around or a formed image may bleed because a formed
ink-receiving layer cannot sufficiently absorb the water of the
ink. When the applied amount exceeds 60.0 g/m.sup.2, a formed
recording medium may cause curling when dried and may not provide
so excellent printing performance as has been expected.
[0054] The reason why a recording medium with the use of a
substrate according to the present invention as described above can
inhibit an image from bleeding out under high-temperature and
high-humidity environment is not clear, but is considered to be
caused by the following phenomenon. In the case of the recording
medium using a non-absorptive substrate such as resin-coated paper,
the bleeding is considered to occur since a high boiling solvent
contained in ink diffuses together with a dye into a receiving
layer. On the other hand, in the case of the recording medium
according to the present invention, it is presumed that a dye in
the ink is adsorbed by alumina particles in the ink-receiving
layer, the organic solvent permeates into the resin layer, thus the
coloring material and the organic solvent are separated, and
accordingly the solvent and the dye do not diffuse together with
each other.
[0055] Ink to be used for recording an image on a recording medium
according to the present invention is not limited in particular,
but is preferably an aqueous ink used for general ink jet
recording, which employs a mixture of water and a water-soluble
organic solvent as a medium and contains a dye or pigment of a
coloring material dissolved or dispersed in the mixture.
[0056] A particularly suitable method for applying the above
described ink to the above described recording medium to form an
image is an ink jet recording method. Any method can be employed as
the ink jet recording method as long as it effectively releases the
ink from a nozzle and applies the ink to the recording medium. A
particularly effectively usable method is an ink jet system which
rapidly changes an ink volume by applying thermal energy to the ink
and ejects the ink from a nozzle by using an acting force generated
by the volume change, and which is described in Japanese Patent
Application Laid-Open No. S54-59936.
EXAMPLES
[0057] Next, the present invention will be more specifically
described with reference to Examples. In the following examples,
"part" and "%" are based on mass unless otherwise described.
[0058] <Production of Substrate (A)>
[0059] A substrate (A) was produced by the steps of preparing a
woodfree paper (with a thickness of 145 .mu.m, basis weight of
147.8 g/m.sup.2 and smoothness of 153 seconds) as a base material
and a cellophane film as a material for a resin layer (with
thickness of 21 .mu.m, basis weight of 29.5 g/m.sup.2, contact
angle of 22.3.degree. and water vapor transmission rate of 710
g/m.sup.2/24 hr); applying a mixture product of adhesives (mixture
of trade name TAKELAC A-520 and trade name TAKENATE A-50 (made by
Mitsui Takeda Chemicals, Inc.) with a mixture ratio of
A-520/A-50=4/1 and solid concentration of 25% after having been
mixed and diluted) onto the above described cellophane film so as
to have a dry coating weight of 6 g/m.sup.2 with the use of a
gravure coater; drying it; and then laminating it on the woodfree
paper. The obtained substrate was subjected to the test of the
following evaluation 1.
[0060] <Production of Substrate (B)>
[0061] A substrate (B) was produced by the same method as the
method for producing the substrate (A) except that a coat paper
(with a thickness of 178 .mu.m, basis weight of 160.4 g/m.sup.2 and
smoothness of 230 seconds) was used instead as a base material in
the method for producing the substrate (A); and was subjected to
the test of the following evaluation 1.
[0062] <Production of Substrate (C)>
[0063] A substrate (C) was produced by the same method as the
method for producing the substrate (A) except that a polyvinyl
alcohol film (with a thickness of 30 .mu.m, contact angle of
28.5.degree. and water vapor transmission rate of 370 g/m.sup.2/24
hr) was used instead as a material for a resin layer in the method
for producing the substrate (A); and was subjected to the test of
the following evaluation 1.
[0064] <Production of Substrate (D)>
[0065] A substrate (D) was produced by the same method as the
method for producing the substrate (B) except that a polyvinyl
alcohol film (with a thickness of 30 .mu.m, contact angle of
28.5.degree. and water vapor transmission rate of 370 g/m.sup.2/24
hr) was used instead as a material for a resin layer in the method
for producing the substrate (B); and was subjected to the test of
the following evaluation 1.
[0066] <Production of Substrate (E)>
[0067] A substrate (E) was produced by the same method as the
method for producing the substrate (A) except that a polyvinyl
alcohol film (with a thickness of 65 .mu.m, contact angle of
32.3.degree. and water vapor transmission rate of 100 g/m.sup.2/24
hr) was instead used as a material for a resin layer in the method
for producing the substrate (A); and was subjected to the test of
the following evaluation 1.
[0068] <Production of Substrate (F)>
[0069] A substrate (F) was produced with reference to a
conventionally well-known method for producing a cellulose casing
by the steps of applying viscose onto a woodfree paper (with a
thickness of 145 .mu.m, basis weight of 147.8 g/m.sup.2 and
smoothness of 153 seconds); and converting it into a regenerated
cellulose film with a thickness of 30 .mu.m. The surface of the
cellulose film had a contact angle of 23.5.degree. and a water
vapor transmission rate of 590 g/m.sup.2/24 hr (the water vapor
transmission rate of the cellulose film is a value obtained by
subtracting the water vapor transmission rate of a base material
from the water vapor transmission rate of the substrate (F)). The
obtained substrate was subjected to the test of the following
evaluation 1.
[0070] <Substrate (G)>
[0071] A substrate (G) was produced by using a polyethylene-coated
paper (having a polyethylene-coated layer with a thickness of 30
.mu.m, contact angle of 96.8.degree., water vapor transmission rate
of 15 g/m.sup.2/24 hr and 60-degree specular glossiness of 64%
according to JIS-Z-8741); and was subjected to the test of the
following evaluation 1.
[0072] <Evaluation 1: Evaluation Method for Ink Absorbency of
Substrate>
[0073] Ink absorbency was evaluated by the steps of conducting
solid printing with a black ink (with a shot-in quantity of ink of
100%) on the surface of a resin layer of a substrate with the use
of an inkjet printer (BJ F870, trade name, made by Canon Inc.);
leaving the substrate at 23.degree. C. and 50% RH for 24 hours; and
confirming a dried state by touching the printed part with a
finger. When the ink was not transferred onto the finger, the
substrate was evaluated to be "A", when a small amount of a dye was
transferred onto the finger, the substrate was evaluated to be "B",
and when the ink was not completely dried and was transferred onto
the finger, the substrate was evaluated to be "C". The result is
shown in Table 1. TABLE-US-00001 TABLE 1 resin layer water vapor
contact transmission evaluation 1 base angle rate thickness ink
substrate material material (.degree.) (g/m.sup.2/24 hr) (.mu.m)
absorbency A woodfree cellophane 22.3 710 21 A paper (cellulose) B
coat cellophane 22.3 710 21 A paper (cellulose) C woodfree
polyvinyl 28.5 370 30 A paper alcohol D coat polyvinyl 28.5 370 30
A paper alcohol E woodfree polyvinyl 32.3 100 65 B paper alcohol F
woodfree cellulose 23.5 590 30 A paper G woodfree polyethylene 96.8
15 30 C paper
[0074] <Production of Alumina Hydrate and Liquid
Dispersion>
[0075] Aluminum dodecanoxide was produced with a method described
in U.S. Pat. No. 4,242,271. Subsequently, this aluminum
dodecanoxide was hydrolyzed to produce an alumina slurry with the
method described in U.S. Pat. No. 4,202,870. Water was added to the
alumina slurry till the alumina hydrate solid content reached 7.7%.
At this time, the pH of the alumina slurry was 9.4. The pH was
adjusted by adding a nitric acid solution of 3.9%. A colloidal sol
was obtained by subsequently aging the slurry in an autoclave in
conditions of a pH of 6.0, an aging temperature of 150.degree. C.
and an aging period time of six hours. The colloidal sol was
spray-dried at an inlet temperature of 87.degree. C. to obtain
alumina hydrate powder.
[0076] An alumina liquid dispersion with a solid concentration of
20% was further prepared by adding 27.3 parts of the thus obtained
alumina hydrate, 9.10 parts of a 6% aqueous acetic acid solution
(2% with respect to alumina hydrate) to 100 parts of ion-exchange
water, and stirring it at 350 rpm for 10 minutes with the use of a
three-one motor (trade name: BL600 made by Shinto Scientific Co.).
In addition, the thus obtained alumina liquid dispersion was dried
at 60.degree. C., and was disintegrated into powder. As a result of
having analyzed the crystal structure of the powder with the use of
an X-ray diffractometer (X'Pert-PRO made by PANalytical
Corporation), the powder showed a boehmite structure. Furthermore,
after having vacuum-deaired the above described powder at
120.degree. C. for 24 hours, the BET specific surface area was
measured with the use of a specific surface area/pore distribution
measuring instrument (trade name: TriSter3000, made by
Micromeritics Corporation (Shimadzu Corporation), adsorption gas:
nitrogen), and was found to be 139.7 m.sup.2/g.
Example 1
[0077] A coating slip was prepared by the steps of adding 0.4 parts
of boric acid (20% with respect to polyvinyl alcohol) into 100
parts of the previously-prepared alumina liquid dispersion; further
adding 20 parts of a 10% aqueous solution of polyvinyl alcohol
(PVA224 made by Kuraray Co.) (10% with respect to alumina hydrate);
and stirring it with a three-one motor until becoming a homogeneous
state. A recording medium according to the present invention was
prepared by applying the thus prepared coating slip onto a
substrate (A) with a Mayer bar so as to have a dry coating amount
of 35 g/m.sup.2 followed by drying with a blast constant
temperature dryer (trade name: FC-610, made by Toyo Engineering
Works Co.) at 110.degree. C. for 20 minutes. The obtained recording
medium was subjected to the following evaluations 2 to 5.
[0078] Various properties of the thus obtained recording medium
were evaluated in the following procedure.
[0079] <Evaluation 2: Evaluation Method for Glossiness>
[0080] With the use of a glossmeter (trade name: VG-2000, made by
Nippon Denshoku Industries Co.), the 20-degree specular glossiness
and 75-degree specular glossiness were measured for the surface of
the ink-receiving layer of a recording medium according to
JIS-Z-8741. The obtained values are shown in Table 2.
[0081] <Evaluation 3: Evaluation Method for Printing
Density>
[0082] Printing density was evaluated by conducting solid printing
of a single color with a black (Bk) ink, cyan (C) ink, magenta (M)
ink and yellow (Y) ink on the above prepared recording medium with
the use of an inkjet printer (trade name: BJ F870, made by Canon
Inc.) with a shot-in amount of ink of 100%; and measuring the
optical density of each solid-printed color with the use of an
optical reflectance densitometer (RD-918 made by Gretag Macbeth
Corporation) The obtained values are shown in Table 2.
[0083] <Evaluation 4: Evaluation Method for Ink
Absorbency>
[0084] Ink absorbency was evaluated by conducting solid printing of
a green color (ink mixing ratio of cyan/photo-cyan/yellow of
85/90/100) on a recording medium in a shot-in ink amount range of
90 to 270% with the use of an inkjet printer (trade name: BJ F870,
made by Canon Inc.); and determining the maximum shot-in amount
which did not cause beading. A recording medium which showed a
maximum shot-in amount of ink of 200% or more was evaluated as "A";
a recording medium which showed a maximum shot-in amount of ink of
170% or more but less than 200% was evaluated as "B"; and a
recording medium which showed a maximum shot-in amount of ink of
less than 170% was evaluated as "C". The result is shown in Table
2.
[0085] <Evaluation 5: Evaluation Method for Image Bleeding Under
High-Temperature and High-Humidity Environment>
[0086] Image bleeding was evaluated by conducting solid printing of
a black color (ink mixing ratio of cyan/magenta/yellow of 50/50/50,
and with shot-in amount of ink of 150%) on a recording medium with
the use of an inkjet printer (trade name of BJ F870 made by Canon
Inc.); and exposing it to an environment of 30.degree. C. and 80%
RH for one week; and evaluating the degree of bleeding of an image
by visual inspection. A recording medium which did not cause
bleeding was evaluated as "A"; a recording medium which slightly
caused bleeding was evaluated as "B"; and a recording medium which
greatly caused bleeding was evaluated as "C". The result is shown
in Table 2.
Examples 2 to 6>
[0087] Recording media were prepared by the same method as in
Example 1 except that the substrate (A) was changed to substrates
(B) to (F) in Example 1; and was subjected to the tests of the
evaluation 2 to 5. The result is shown in Table 2.
Comparative Example 1
[0088] A recording medium was prepared by the same method as in
Example 1 except that the substrate (A) was changed to a woodfree
paper (with a thickness of 145 .mu.m, basis weight of 147.8
g/m.sup.2 and smoothness of 153 seconds) in Example 1; and was
subjected to the tests of the evaluation 2 to 5. The result is
shown in Table 2.
Comparative Example 2
[0089] A recording medium was prepared by the same method as in
Example 1 except that the substrate (A) was changed to a woodfree
paper (with a thickness of 178 .mu.m, basis weight of 160.4
g/m.sup.2 and smoothness of 230 seconds) in Example 1; and was
subjected to the tests of the evaluation 2 to 5. The result is
shown in Table 2.
Comparative Example 3
[0090] A recording medium was prepared by the same method as in
Example 1 except that the substrate (A) was changed to the
substrate (G) and the coating slip was applied on the
polyethylene-coated layer of which the surface had been treated
with corona discharge; and was subjected to the tests of the
evaluation 2 to 5. The result is shown in Table 2.
Comparative Example 4
[0091] A recording medium was prepared by the same method as in
Example 1 except that 0.667 parts of a cationic polymer (trade
name: PAS-A-120L, 30% aqueous solution, weight average molecular
weight: about 100,000, produced by Nitto Boseki Co.) (1% with
respect to alumina hydrate) was added into the coating slip, and
further the substrate (A) was changed to the substrate (G) of which
the surface of a polyethylene-coated layer had been treated with
corona discharge; and was subjected to the tests of the evaluation
2 to 5. The result is shown in Table 2. TABLE-US-00002 TABLE 2
Evaluation 5 image bleeding Evaluation 4 under high- ink
temperature Evaluation 2 Evaluation 3 absorbency and high-
glossiness printing density shot-in humidity substrate 20.degree.
75.degree. Bk C M Y amount environment Example 1 A 21.4 63.0 2.24
2.63 2.32 2.25 A A Example 2 B 21.8 61.7 2.29 2.63 2.34 2.30 A A
Example 3 C 21.5 62.5 2.27 2.56 2.28 2.23 A A Example 4 D 22.0 63.2
2.24 2.58 2.30 2.24 A A Example 5 E 23.1 63.5 2.32 2.61 2.31 2.27 A
B Example 6 F 13.2 53.5 2.18 2.52 2.27 2.15 A A Comparative
woodfree 3.1 38.2 2.25 2.59 2.32 2.30 A A Example 1 paper
Comparative coat 3.5 43.5 2.15 2.45 2.21 2.11 A A Example 2 paper
Comparative G 19.2 58.7 2.17 2.50 2.20 2.12 B C Example 3
Comparative G 19.3 59.2 2.08 2.44 2.10 1.91 B C Example 4
[0092] As is clear from Table 2, the recording medium produced with
the use of the substrate according to the present invention showed
high glossiness and high printing density, and enabled recording of
a high-quality image. The substrate according to the present
invention also showed excellent ink absorbency and an effect of
preventing the image from bleeding under high-temperature and
high-humidity environment, in comparison with polyethylene-coated
paper.
[0093] With the present invention, an ink-receiving layer superior
in glossiness can be formed without smoothing treatment, by using a
substrate comprising a base material and a resin layer with ink
absorbency and/or ink permeability provided on the base material,
and further a recording medium which has excellent image density
and ink absorbency can be provided, which effectively prevents an
image from bleeding under high-temperature and high-humidity
environment.
[0094] While the invention has been described with reference to the
preferred embodiments disclosed herein, it is not confined to the
details set forth and this application is intended to cover such
modifications or changes as may come within the purpose of the
improvements or the scope of the appended claims.
[0095] This application claims priority benefits of Japanese Patent
Applications No. 2005-216533 filed Jul. 26, 2005 and No.
2006-167645 filed Jun. 16, 2006 the entire disclosures of which are
incorporated herein by reference in their entirety.
* * * * *